UNIVERSITY  OF  CALIFORNIA  PUBLICATIONS. 


COLLEGE  OF  AGRICULTURE. 

AGRICULTURAL  EXPERIMENT  STATION. 


DIRECTIONS  FOR  SPRAYING 


FOR    THE 


CODLING-MOTH. 


By  C.  W.  WOODWORTH. 


BULLETIN   No.   155. 

(Berkeley,  March,  1904.) 


SACRAMENTO: 

w.  w.  shannon,    :    :    :    :    :    superintendent  state  printing. 

1  904. 


BENJAMIN  IDE  WHEELER,  Ph.D.,  LL.D.,  President  of  the  University. 

EXPERIMENT  STATION  STAFF. 

E.  W.  HILGARD,  Ph.D.,  LL.D.,  Director  and  Chemist. 

E.  J.  WICKSON,  M.A.,  Horticulturist,  and  Superintendent  of  Central  Station  Grounds. 

W.  A.  SETCHELL,  Ph.D.,  Botanist. 

ELWOOD  MEAD,  M.S.,  C.E.,  Irrigation  Engineer. 

R.  H.  LOUGHRIDGE,  Ph.D.,  Agricultural  Geologist  and  Soil  Physicist.    {Soils  and  Alkali.) 

C.  W.  WOODWORTH,  M.S.,  Entomologist. 

M.  E.  JAFFA,  M.S.,  Assistant  Chemist.    (Foods,  Nutrition  ) 

G.  W.  SHAW,  M.A.,  Ph.D.,  Assistant  Chemist.    (Soils,  Beet-Sugar.) 

GEORGE  E.  COLBY,  M.S.,  Assistant  Chemist.    (Fruits,   Waters,  Insecticides.) 

RALPH  E.  SMITH,  B.S.,  Plant  Pathologist. 

A.  R.  WARD,  B.S.A.,  D.V.M.,  Veterinarian,  Bacteriologist. 

E.  H.  TWIGHT,  B.Sc,  Diplome  E.A.M.,  Viticulturist. 

E.  W.  MAJOR,  B.Agr.,  Animal  Industry. 

A.  V.  STUBENRAUCH,  M.S.,  Assistant  Horticulturist,  in  charge  of  Substations. 

WARREN  T.  CLARKE,  B.S.,  Assistant  Field  Entomologist. 

H.  J.  QUAYLE,  A.B.,  Assistant  Entomologist. 

H.  M.  HALL,  M.S.,  Assistant  Botanist. 

GEORGE  ROBERTS,  M.S.,  Assistant  Chemist,  in  charge  Fertilizer  Control. 

('.  A.  TRIEBEL,  Ph.G.,  Assistant  in  Agricultural  Laboratory. 

C.  A.  COLMORE,  B.S.,  Clerk  to  the  Director. 


EMIL  KELLNER,  Foreman  of  Central  Station  Grounds. 

JOHN  TUOHY,  Patron,  ) 

•   Tulare  Substation,  Tulare. 
JULIUS  FORRER,  Foreman,  \ 

J.  E.  McCOMAS,  Patron,  Pomona,  \ 

J.  W.  MILLS,  Superintendent,  Ontario,  >■  Southern  California  Substation. 

JOHN  H.  BARBER,  Assistant  Superintendent,  Ontario,   ) 

A.  A.  KNOWLTON,  Patron,  ) 

t    tt    r.^T  „v    „r    ,  •  f   University  Forestry  Station,  Chico. 

J.  H.  OOLE  1 ,  Workman  in  charge,  ) 

ROY  JONES,  Patron,        ) 

.....    urTTTrnrn    „  t   University  Forestry  Station,  Santa  Monica. 

\\M.  S1ILTT,  Foreman,     \ 

II.  O.  WOODWORTH,  M.S.,  Foreman  in  charge,  Poultry  Station,  Petaluma. 


The  Station  publications  (Reports  and  Bulletins),  so  long  as  avail- 
able, will  be  sent  to  any  citizen  of  the  State  on  application. 


DIRECTIONS  FOR  SPRAYING  FOR  THE 
CODLING-MOTH. 


The  present  bulletin  has  been  prepared  for  the  purpose  of  placing  in 
the  hands  of  growers  of  apples  and  pears  a  concise  statement  of  the 
recommendations  for  the  control  of  the  codling-moth,  based  on  the 
results  of  the  investigation  of  this  insect  conducted  the  past  season  in 
the  Pajaro  Valley.  This  work  was  undertaken  at  the  request  of  the 
Orchard  Association,  with  funds  provided  by  the  Boards  of  Supervisors 
of  Santa  Cruz  and  Monterey  counties.  The  detailed  discussion  of  the 
results  of  these  studies  will  be  presented  in  a  series  of  bulletins,  which 
will  be  sent  on  application  to  those  especially  interested.  We  hope 
that  the  present  publication  will  also  enable  us  to  secure  the  co-opera- 
tion of  growers  in  every  section  of  the  State  in  making  the  observations 
suggested  herein,  so  that  a  more  complete  knowledge  may  be  obtained 
of  the  facts  upon  which  the  rational  treatment  of  the  insect  must  be 
based. 

ARSENICAL    SPRAYS    THE    REMEDY. 

There  have  been  a  great  many  suggestions  as  to  different  ways  of 
controlling  the  codling-moth,  and  all  that  have  come  to  our  attention, 
that  offered  any  prospect  of  even  partial  results,  have  been  tested  and 
found  wanting,  with  the  single  exception  of  the  arsenical  sprays. 

Possibly,  at  some  future  time,  some  other  effective  means  may  be 
discovered  that  will  be  as  good,  or  better  than  the  arsenicals,  but  up  to 
the  present  time  these  substances  stand  far  in  the  lead,  and  it  is  not 
wise  for  the  orchardist  to  experiment,  except  on  the  smallest  scale,  with 
anything  else. 

That  any  of  the  standard  arsenicals  constitute  an  effective  remedy 
appears  to  be  well  demonstrated,  for  in  every  part  of  the  Pajaro  Valley 
apple  district,  in  which  we  conducted  experiments,  it  was  found  possi- 
ble to  reduce  the  injury  to  a  very  satisfactory  percentage  when  the 
poison  was  properly  applied. 

Which  Arsenicals  to   Use. 

Paris  Green. — The  material  which  has  been  most  widely  used  for 
fighting  this  insect  is  paris  green,  and  for  effectiveness  against  the  insect 
none  of  the  other  arsenicals  are  any  better  at  the  same  strength  of 
arsenic.  The  amount  most  commonly  used  and  found  very  satisfactory 
is  one  pound  for  one  hundred  and  fifty  gallons. 

There  are  a  good  many  localities  where  paris  green  is  liable  to  injure 


4  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION. 

the  tree,  and  this  injury  can  easily  be  greater  than  any  possible  saving 
of  fruit  effected  by  the  destruction  of  the  worm.  Not  only  will  it  result 
in  small  apples,  but,  if  too  severe,  may  also  affect  the  crop  of  the  following 
season.  In  most  of  these  regions  the  danger  of  injury  can  be  avoided 
by  the  addition  of  lime.  The  amount  added  to  the  spraying  mixture 
should  be  the  greater  the  more  susceptible  the  trees  are  to  injury.  The 
regions  in  which  the  trees  are  most  liable  to  injury  are  those  where 
dews  and  fogs  are  the  most  prevalent.  Five  or  ten  times  as  much  lime 
as  paris  green  is  the  proportion  recommended  in  these  more  moist 
regions. 

Lime  Arsenite. — In  the  lower  portion  of  the  Pajaro  Valley  the  dan- 
ger of  poisoning  the  foliage  is  so  great,  even  when  the  maximum 
amount  of  lime  is  added,  that  we  can  not  recommend  the  use  of  paris 
green  at  all,  but  suggest  the  substitution  of  the  lime  arsenite,  or  lead 
arsenate. 

Lime  arsenite  may  be  made  according  to  either  of  the  two  following 
formulas: 

The  Taft  Formula:  Boil  one  pound  of  (white)  arsenic  and  two  pounds 
of  lime  in  two  gallons  of  water  for  forty  minutes,  and  then  dilute  as 
required.  One  pound  of  the  arsenic,  prepared  as  above,  is  used  in  every 
three  hundred  to  four  hundred  gallons  of  water. 

The  Kedzie  Formula:  Boil  two  pounds  of  white  arsenic  with  eight 
pounds  of  sal-soda  in  two  gallons  of  rain  water.  Boil  these  materials 
together  in  any  iron  pot  not  used  for  other  purposes;  boil  them  fifteen 
minutes,  or  until  the  arsenic  dissolves,  leaving  only  a  small  muddy 
sediment.  Put  the  solution  in  a  two-gallon  jug  and  label  "  Poison — 
Stock  Material  for  Spraying  Mixture."  The  spraying  mixture  can  be 
prepared  whenever  required,  in  the  quantity  needed  at  the  time,  by 
slaking  two  pounds  of  lime  and  adding  this  to  forty  gallons  of  water; 
pour  into  this  a  pint  of  the  stock  arsenic  solution;  mix  up,  stirring 
thoroughly,  and  the  spraying  mixture  will  be  ready  for  use. 

Either  of  these  mixtures  when  carefully  made  is  almost  or  quite  as 
effective  against  the  worm,  and  distinctly  safer  to  the  foliage,  than 
paris  green.  The  cheaper  cost  of  this  material  and  the  greater  ease  of 
keeping  it  mixed  while  spraying  are  advantages  that  partly  offset  the 
trouble  of  preparing  it.  Arsenite  of  lime  is  very  satisfactory  where  one 
can  buy  it  already  prepared  and  is  assured  of  the  honesty  and  careful- 
ness of  the  manufacturer.  When  buying  it  in  this  form  there  is  usually 
no  gain  over  paris  green  in  the  matter  of  cost,  and  often  it  is  really  the 
more  expensive. 

Lead  Arsenate. — rJ^he  arsenate  of  lead  is  by  all  odds  the  safest  of  the 
arsenicals  that  have  come;  into  use  as  regards  their  effect  on  the  foliage. 
It  appears  to  be  also  distinctly  less  fatal  to  tin;  codling-moth  than  the 


DIRECTIONS    FOR    SPRAYING    FOR    THE    CODLING-MOTH. 


same  relative  strength  of  paris  green,  or  of  arsenite  of  lime.  There 
are  two  methods  of  making  this  arsenical.  In  each  method  68%  arsenate 
of  soda  is  used,  and  with  this,  in  one  case,  the  ordinary  white  granular 
acetate  of  lead,  and  in  the  other,  lead  nitrate.  The  process  of  manu- 
facture is  as  follows:  The  lead  salt  and  arsenate  of  soda  are  dissolved 
separately,  and  then  poured  into  the  tank  containing  the  water  for 
spraying.  The  proportions  used  are  about  as  follows:  For  every  ten 
ounces  of  arsenate  of  soda  take  twenty-four  ounces  of  lead  acetate  or 
twenty  ounces  of  lead  nitrate.  These  substances  can  be  purchased  in 
the  right  proportions  and  tied  up  in  bags,  so  that  it  will  require  one 
bagful  of  each  for  each  tank  of  water. 

From  the  results  obtained  the  past  season  we  would  recommend  the 
use  of  a  mixture  containing  distinctly  more  arsenic  than  if  other 
arsenicals  were  used;  or  the  amounts  given  above  for  each  one  hundred 
gallons.  As  a  precautionary  matter,  it  might  be  well  to  test  the  mix- 
ture in  order  to  be  sure  that  the  arsenic  is  all  in  combination;  this 
can  be  done  by  the  use  of  po- 
tassium bi-chromate,  which 
will  produce  a  yellow  pre- 
cipitate if  the  solution  con- 
tains lead  in  excess,  as  it 
should. 


Paris  Green,  Oil  and 
Lime. — A  new  spraying  mix- 
ture was  developed  last 
season  too  late  for  a  test  in 
the  orchards  sufficient  to  be 
positively  recommended,  but 
it  promises  to  be  the  best 
solution  of  the  problem  of 
preventing  injury  to  foliage 
by  paris  green.  This  con- 
sists in  coating  the  particles 
of  the   paris  green   with  an 

infinitesimal  quantity  of  oil,  which  will  prevent  its  being  wetted  by  fog 
or  dew,  thus  rendering  it  almost  absolutely  harmless  to  the  plant.  The 
spray  mixture  may  be  made  as  follows:  Stir  one  pound  of  paris  green 
into  a  pint  of  crude  oil  (petroleum);  slake  four  or  five  pounds  of  lime; 
add  the  paris  green  and  oil,  and  stir  well,  so  that  the  lime  will  unite 
with  the  excess  of  oil;  then  dilute  to  one  hundred  and  fifty  gallons, 
and  it  is  ready  to  apply. 

This  mixture  will  be  tested  very  thoroughly  the  coming  season. 


Fig.  1.  Microscopical  appearance  of  spraying  mix- 
tures, showing  one  sphere  of  paris  green  and 
many  particles  of  lime. 


6  UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION. 

WHEN    AND    HOW   TO   SPRAY. 

These  are  questions  that  each  orchardist  must  in  some  measure 
answer  for  himself,  for  no  precise  statement  can  be  made  that  will 
cover  any  large  region,  or  possibly  any  two  succeeding  years  in  the 
same  orchard. 

There  is  enough  difference  in  the  problem  of  controlling  the  codling- 
moth,  even  in  the  single  horticultural  region,  the  Pajaro  Valley,  to 
require  an  essentially  different  program  in  its  different  parts.  Doubt- 
less other  sections  of  the  State  will  require  still  greater  differences  in  the 
method  of  handling  the  codling-moth  than  are  necessary  in  the  region 
that  was  under  investigation.  All  the  spraying  operations  should  be 
made  to  depend  upon  data  determined  for  each  region  as  to  certain 
essential  facts  in  regard  to  the  history  of  the  codling-moth  and  of  the 
trees.  These  facts  are  not  difficult  to  obtain,  and  there  is  no  reason 
why  any  grower  of  apples  might  not  make  the  necessary  observations 
to  determine  the  proper  time  for  these  spraying  operations. 

Under  the  worst  conditions  there  will  be  the  necessity  for  making 
three  campaigns  each  season  against  the  insect.  In  many  regions  one 
or  two  of  these  might  be  omitted.  How  much  can  be  omitted  and  the 
times  for  the  beginning  and  end  of  each  campaign,  will  have  to  be 
determined  for  each  locality. 

THE    FIRST   CAMPAIGN. 

The  first  campaign  is  the  one  based  upon  the  blossoming  of  the  trees. 
There  is  a  short  period,  just  immediately  after  the  petals  fall  from  the 
fruit,  when  it  is  possible  by  properly  spraying  the  trees  to  place  suffi- 
cient poison  within  the  cup  formed  by  the  calyx  lobes  to  effectively 
destroy  any  worms  that  may  thereafter  attempt  to  enter  the  apple  at 
that  place. 

Most  recent  reports  on  the  codling-moth  have  dwelt  with  much 
emphasis  on  the  necessity  of  properly  timing  this  application;  and  our 
observations  have  indicated  additional  grounds  for  its  efficiency,  par- 
ticularly the  ascertainment  of  the  fact  that  the  young  worm,  on  attempt- 
ing to  enter  an  apple  at  this  place,  regularly  spends  a  considerable 
period  within  the  cup,  feeding  upon  the  surface  of  the  fruit,  but  not 
injuring  it  in  any  appreciable  way.  During  this  time  the  presence  of  a 
small  amount  of  poison  would  be  almost  certain  to  be  destructive  to  the 
insect — its  death  being  brought  about  before  it  enters  the  fruit;  and  so 
the  apple  will  be  protected.  The  important  point  to  determine,  in  order 
to  make  these  sprayings  effective,  is  the  exact  time  when  the  first  blos- 
soms have  dropped  their  petals  (as  the  beginning  of  the  first  spraying 
period)  and  the  time  that  these  first  blossom-cups  have  sufficiently 
closed  to  make  this  spraying  ineffectual  (as  the  end  of  the  first  spraying 


DIRECTIONS    FOR    SPRAYING    FOR   THE    CODLING-MOTH. 


period).  During  this  period  there  should  be  a  thorough  application  of 
the  poison,  in  order  to  fill  these  early  blossom-cups.  There  may  be  a 
few  varieties  in  some  localities,  in  which  all  the  blossoms  open  nearly 
enough  together  so  that  practically  everything  is  accomplished  by  a 
single  spraying.  In  most  parts  of  the  State,  however,  the  blooming  of 
all  varieties  extends  over  a  considerable  period  of  time,  during  which  it 
will  be  necessary  to  make  two,  or  even  three,  applications,  in  order  to 
accomplish  this  result;  for  instance,  at  one  time  blossoms  and  fruit 
were  picked  from  about  the  same  part  of  one  apple  tree,  representing 
all  the  stages  of  development  shown  in  Fig.  2. 

It  will  not  do,  as  is  often  .recommended,  to  wait  until  the  majority 
of  the  blossoms  are  in  about  the  right  condition  and  then  attempt  to 
make  one  spraying  accomplish  the  work.  In  one  instance,  where  we 
made  a  definite  determination  of  the  blossoms  setting  on  an  apple  tree, 
every  blossom  that  finally  produced  fruit  had  already  passed  the  con- 
dition in  which  it  was  possible  to  place  poison  in  the  cup  before  the  major- 


Fig.  2.    Blossoms  and  Fruit  on  tree  at  one  time. 

ity  of  the  blossoms  on  the  tree  had  dropped  their  petals.  It  would 
certainly  not  do,  as  has  been  recommended,  to  wait  until  practically  all 
blossoms  had  fallen,  because,  at  least  under  the  conditions  prevailing  in 
the  Watsonville  district,  the  fruit  setting  on  the  trees  may  have  attained 
considerable  size,  as  in  the  case  just  cited.  There  is  almost  always  a  con- 
siderable difference  in  the  average  time  of  blooming  of  the  branches  in  the 
top  of  the  tree  from  those  near  the  bottom;  so  that,  if  it  could  be  ascer- 
tained that  in  any  region  only  the  early  blossoms  on  the  branch  would 
produce  fruit,  still  more  than  one  application  would  have  to  be  made 
to  effectively  treat  the  higher  and  lower  fruit. 

Only  in  those  regions  where  the  conditions  are  such  that  this  first 
campaign  can  be  omitted  entirely,  will  the  neglect  of  carefully  deter- 
mining the  time  of  blooming  fail  to  result  in  loss. 

The  method  of  spraying  in  this  first  campaign  should  be  essentially 
different  from  that  later  in  the  year  in  this  particular,  viz.,  that  the 
object  is  to  poison  the  blossom-cup.  It  will  be  a  waste  of  energy  to 
spray  anywhere  except  against  the  blossoms  from  above.  It  is  only  the 
spray  which  comes  down  into  the  blossom  that  can  have  any  effect* 


8 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION. 


There  are  two  methods  of  accomplishing  this:  First,  the  nozzle  may 
be  held  in  such  a  position  that  it  will  be  directed  down  over  the  blos- 
soms and  the  spray  mixture  applied  with  considerable  force;  the  inten- 
tion being  to  thoroughly  drench  these  parts  of  the  plant  from  above,  so 
as  to  cause  the  poison  to  lodge  among  the  hairs  covering  the  whole 
interior  of  the  cup. 

The  other  method  is  to  throw  the  water  into  the  air,  above  the  blos- 
soms, in  a  fine  mist,  the  actual  direction  of  the  nozzle  being  of  little 


Fig.  3.    Spraying  outfit  in  operation. 

consequence.  The  fog  thus  produced  is  allowed  to  settle  gently  on  the 
parts  which  it  is  desired  to  wet  and  the  spraying  kept  up  until  every- 
thing has  been  completely  wetted.  This  will  require  a  much  longer  time, 
but  is  probably  somewhat  more  economical  in  material;  either  method 
will  accomplish  the  results  aimed  at,  viz:  the  poisoning  of  the  blossom- 
cup. 

The  aim  of  most  of  the  sprayers  whose  work  has  been  studied  is  to 
attempt  to  wet  the  fruit  from  beneath;  indeed,  this  mistake  is  practically 
universal  among  California  sprayers.  In  a  very  few  cases  elevated  plat- 
form- are  used  (something  like  that  shown  in  Fig.  3),  from  which  it  is 


DIRECTIONS   FOR   SPRAYING   FOR   THE   CODLING-MOTH.  9 

We  desire  to  secure  the  co-operation  of  orchardists  in  all  parts  of  the  State  in  making 
observations  upon  the  blossoming  time  of  the  different  varieties  of  apples  and  pears 
in  each  section.  Blanks  like  the  following  will  be  sent  to  any  who  will  volunteer  in 
this  work. 

BLOSSOMING  RECORD 

To  Determine  Date  to  Spray  for  Codling-Moth  in  First  Campaign. 

Name  of  observer 

Address 

Location  of  trees  under  observation 

Variety 

FIRST  SPRAYING. 

Date  of  first  blossoms 1904. 

Mark  a  number  of  blossoms  by  tying  a  bit  of  white  yarn  loosely  around  stem  of  blossom. 

Date  of  petals  falling 1904. 

Spray  before  cups  close. 

Actual  date  of  spraying 1904. 

Date  of  cup  closing 1904. 

Per  cent  of  blossoms  open  at  last  date per  cent. 

SECOND  SPRAYING. 

Mark  a  number  of  blossoms  just  opening  at  last  date  above,  using  red  yarn. 

Date  of  petals  falling 1904. 

Spray  before  cups  close.    Combine  with  second  campaign,  if  moths  have  begun  to  emerge. 

Actual  date  of  spraying 1904. 

Date  of  cup  closing 1904. 

Per  cent  of  blossoms  open  at  last  date per  cent. 

THIRD  SPRAYING. 

Mark  a  number  of  blossoms  just  opening  at  last  date  above,  using  blue  yarn. 

Date  of  petals  falling 1904. 

Spray  before  cups  close.    Combine  with  second  campaign,  if  moths  have  begun  to  emerge. 

Actual  date  of  spraying 1904. 

Date  of  cup  closing 1904. 

Per  cent  of  blossoms  open  at  last  date per  cent. 

If  there  are  any  buds  still  opening,  mark  some  with  brown  yarn.    Should  there  be  more 
than  five  per  cent  of  buds  still  to  open,  continue  these  records  on  the  other  side  of  this  sheet. 

After  the  fruit  has  set  make  the  following  observations: 

Number  Marked.  Number  Set. 

Marked  with  white  yarn  _  

Marked  with  red  yarn 

Marked  with  blue  yarn  _  _  

Marked  with  brown  yarn  

Send  this  record,  when  complete,  to  C.  W.  WOODWORTH,  Agri- 
cultural Experiment  Station,  Berkeley,  California. 


DIRECTIONS    FOR   SPRAYING   FOR   THE    CODLING-MOTH.  11 

possible  to  properly  spray  the  tree.  In  other  cases  where  trees  are  very 
small  a  few  operators  have  learned  to  spray  into  the  air  entirely, 
instead  of  toward  the  tree,  and  using  long  extension  rods  so  that  the 
spray  will  be  carried  to  the  top  of  the  tree  A  nozzle  giving  a  fine  mist 
can  of  necessity  only  force  water  a  short  distance. 

The  best  results  can  only  be  expected  when  much  attention  is  given 
to  both  the  time  and  method  of  spraying. 

THE    SECOND   CAMPAIGN. 

The  second  spraying  campaign  should  be  inaugurated  at  about  the 
time  when  the  first  eggs  are  being  deposited  upon  the  trees.  In  some 
localities  this  may  not  be  far  from  blooming  time,  but  in  others,  as  at 
Watsonville,  it  is  considerably  later,  and  different  in  the  different  parts 
of  the  valley.  The  actual  time  of  egg-laying  can  be  quite  accurately 
determined  by  the  fruit-grower  without  very  much  difficulty.  The  eggs 
themselves  are  quite  small — not  larger  than  a  pin-head — and  flat  and 
transparent,  so  that  one  would  have  to  look  at  them  in  such  a  way  as 
to  get  the  proper  reflection  of  light  from  their  surface  in  order  to  clearly 
distinguish  them  from  the  leaf  or  fruit  on  which  they  lie.  They  will 
be  first  found  in  the  spring  upon  the  upper  side  of  the  older  leaves,  and 
by  careful  search  in  the  orchard  the  time  of  egg-laying  might  be  deter- 
mined by  direct  observation  of  the  egg. 

A  much  simpler  method,  however,  requiring  no  careful  examination 
of  the  trees,  can  be  made  by  means  of  a  breeding  cage;  a  common 
Mason  fruit  jar  with  a  piece  of  cloth  tied  over  the  top,  in  the  place  of 
the  ordinary  metal  cap,  will  be  very  satisfactory.  This  can  be  kept  in 
the  orchard  in  an  old  apple  box,  tacked  to  the  north  side  of  a  tree, 
making  a  sort  of  a  cupboard,  in  which  the  breeding  cage  may  be  placed 
to  protect  it  from  the  weather  and  accidents. 

The  codling-moth  passes  the  winter  in  a  great  variety  of  situations, 
sometimes  in  the  ground,  or  it  may  be  in  cracks  of  the  bark  or  under 
bands  of  cloth,  if  these  have  been  placed  on  the  tree  according  to  the 
method  so  commonly  in  vogue. 

The  insect  is  in  the  worm-form  during  the  winter  just  as  it  was  when 
it  left  the  apple,  but  has  covered  itself  with  a  tough  silken  cocoon,  and 
lies  almost  quiescent  in  this  form  until  spring.  During  the  winter 
these  cocoons  may  be  sought  for  and  placed  in  the  breeding  cage,  and 
the  insects  will  go  through  their  transformation  in  the  spring  and 
appear  as  moths  in  a  perfectly  normal  manner. 

Now,  by  examining  these  breeding  cages  from  week  to  week,  the 
orchardist  can  determine  the  date  of  the  first  hatching  of  the  moths, 
the  time  when  they  are  produced  in  the  greatest  number;  and  if  he 


12 


UNIVERSITY    OF    CALIFORNIA EXPERIMENT    STATION. 


begins  spraying  as  soon  as  this  hatching  occurs  and  continues  it,  say- 
once  every  three  weeks  until  they  cease  to  appear  in  numbers,  he  can 
be  confident  that  he  has  properly  timed  his  spraying  for  the  destruc- 
tion of  the  brood  of  worms  to  be  produced  from  the  eggs  laid  by  these 
moths. 

If  the  moths  hatch  practically  all  together,  as  they  may  in  some 
regions,  a  single  spraying  is  all  that  is  necessary  for  this  campaign. 


Fig.  4.    Cupboard  containing  breeding  cages. 

In  most  regions,  however,  this  will  not  be  found  to  be  the  case,  and  two, 
or  possibly  three,  sprayings  may  be  necessary.  Again,  in  some  localities 
the  first  and  second  campaigns,  as  just  outlined,  may  occur  so  close 
together  that  the  same  spraying  will  poison  the  leaves  and  outer  surface 
of  the  fruit  for  the  young  worms,  and  fill  the  blossom-cups  so  as  to  be 
ready  for  those  that  enter  these  cups  before  feeding  elsewhere. 

The  method  of  spraying  in  this  second  campaign  differs  from  that 
already  described  in  that  the  object  now  becomes  not  to  wet  any  one 
part  of  the  tree  particularly,  but  to  cover  everything  as  uniformly  as 


DIRECTIONS    FOR    SPRAYING    FOR    THE    CODLING-MOTH.  13 

We  desire  to  secure  the  co-operation  of  orchardists  in  all  parts  of  the  State  in  making 
observations  on  the  time  the  codling-moth  emerges  in  the  spring  in  each  section. 
Blanks  like  the  following  and  envelopes  to  contain  specimens  will  be  sent  to  any  who 
will  volunteer  in  this  work. 

EMERGENCE  RECORD 
To  Determine  Date  to  Spray  for  Codling-Moth  in  Second  Campaign. 

Name  of  observer 

Address 

Location  of  breeding  cage 

Number  of  cocoons  placed  in  breeding  cage 

The  breeding  cage  may  consist  of  a  " Mason  fruit  jar"  with  a  piece  of 
cloth  over  the  top  instead  of  the  screw  cap.  Obtain  the  pupae  during 
the  winter  from  old  apple  boxes,  about  the  packing-house,  under  bands 
or  in  cracks  in  the  bark.  Tack  an  apple  box  on  the  north  side  of  a  tree 
as  a  cupboard  to  contain  breeding  cage.  Examine  each  week.  When 
first  moth  appears  record  it  below,  and  continue  records  weekly. 

Date.  FIRST  SPRAYING. 

Found moths.     Put  them  in  envelope  1. 

If  time  to  spray  blossoms  again,  also  spray  foliage  for  young  worms. 

Found moths.     Put  them  in  envelope  2. 

Ii  three  weeks  since  last  spraying  and  ten  per  cent  of  the  cocoons  have  produced  moths, 

spray  at  once. 

Found moths.     Put  them  in  envelope  3. 

If  you  did  not  spray  last  week  or  week  before,  do  so  now. 

Actual  date  of  spraying ,  1904. 

SECOND  SPRAYING. 

Found moths.     Put  them  in  envelope  4. 

If  three  weeks  since  last  spraying,  spray  again. 

Found moths.     Put  them  in  envelope  5. 


If  three  weeks  since  last  spraying  and  if  envelopes  4  and  5  have  as  many  moths  as 
envelopes  3  and  4,  spray  again. 

Found _  moths.     Put  them  in  envelope  6. 


If  three  weeks  since  last  spraying  and  envelope  6  has  as  many  moths  as  the  average 
of  the  others,  spray  again. 

Actual  date  of  spraying ,  1904. 

THIRD  SPRAYING. 

Three  weeks  from  the  second  spraying,  unless  the  number  of  moths  falls  lower  than  the 
average  of  preceding  weeks. 

Found moths.     Put  them  in  envelope  7. 

Found moths.     Put  them  in  envelope  8. 

Found moths.     Put  them  in  envelope  9. 

Found moths.     Put  them  in  envelope  10. 

Found moths.     Put  them  in  envelope  11. 

Actual  date  of  spraying ,  1904. 

Send  the  record  when  complete  and  the  envelopes,  for  the  accurate 
identification  of  moths,  to  C.  W.  WOODWORTH,  Agricultural  Experi- 
ment Station,  Berkeley,  California. 


DIRECTIONS    FOR    SPRAYING    FOR    THE    CODLING-MOTH.  15 

possible  with  the  spray  mixture.  Moreover,  the  surface  which  we  now 
desire  to  wet  is  waxy  in  large  part,  instead  of  being  hairy.  It  is  not 
possible,  therefore,  to  accomplish  good  results  by  the  use  of  a  nozzle 
giving  a  coarse  heavy  spray,  as  may  be  done  in  the  first  spraying. 
There  now  arises,  also,  the  danger  of  over-spraying;  that  is,  of  spraying 
so  long  in  the  same  place  that  the  fine,  mist-like  particles  which  were 
first  quite  uniformly  distributed  over  the  leaf  will  ultimately  run 
together,  often  leaving  large  areas  of  the  smooth  waxy  surface  of  the 
leaves  entirely  free  from  water  and  from  poison,  and  concentrating  the 
poison  that  is  deposited  from  the  larger  drops  of  water  along  the  edges 
of  the  leaves  or  in  the  wrinkles  occurring  along  the  veins,  the  greater 
part  of  the  leaf  being  free  from  poison.  For  this  purpose,  therefore,  a 
nozzle  should  be  selected  which  will  spray  widely  and  produce  the  finest 
separation  of  the  particles  of  water.  Such  a  nozzle  will  only  force  the 
water  a  short  distance,  and  the  mist  formed  will  float  in  the  air  if  a 
gentle  breeze  is  blowing,  making  it  somewhat  difficult  to  spray  on  the 
tree  except  on  the  windward  side. 

If  the  trees  are  large  there  will  be  so  much  advantage  in  an  elevated 
platform  and  extension  rods,  enabling  one  to  reach  into  any  part  of  the 
tree,  that  such  appliances  should  always  be  used.  It  is  well  to  attempt 
to  spray  from  all  directions,  the  object  being  to  cover  the  tree  as 
thoroughly  as  possible,  but  not  to  drench  any  portion;  stopping  long 
before  the  leaves  begin  to  drip.  If  one  has  a  fine  nozzle,  or  a  bunch  of 
small  nozzles  at  the  end  of  the  rod,  and  moves  over  the  tree  rapidly,  it 
can  be  made  very  thoroughly  wet  in  every  part  before  enough  liquid  is 
used  to  produce  this  unsatisfactory  "over-sprayed"  effect. 

During  the  past  season  it  was  observed  in  the  Watsonville  district 
that  a  great  majority  of  the  worms  entered  the  fruit  at  other  places 
than  the  blossom  end,  and  when  this  is  the  case  the  second  campaign 
will  become  much  more  important  than  the  first.  In  other  regions, 
according  to  the  testimony  of  many  investigators,  the  reverse  is  true,  in 
which  case  the  first  campaign  would  evidently  be  the  more  important 
one.  But  even  in  these  regions  undoubtedly  the  second  campaign 
would  produce  good  results,  because  everywhere  a  certain  proportion  of 
worms  entered  at  other  places  than  at  the  blossom  end,  even  while  the 
fruit  was  small. 


16  UNIVERSITY    OF    CALIFORNIA — EXPERIMENT   STATION. 

THE    THIRD    CAMPAIGN. 

The  codling-moth  has  more  than  one  brood  in  all  parts  of  California 
where  apples  and  pears  are  grown  on  a  commercial  scale,  and  in  most 
localities  the  injury  produced  by  the  first  brood  is  insignificant  in  com- 
parison with  that  coming  later  in  the  year.  In  the  Pajaro  Valley  par- 
ticularly, the  orchardists  would  not  consider  the  codling-moth  an 
important  insect  but  for  this  later  work.  The  varieties  grown  in  this 
region  almost  invariably  set  such  an  amount  of  fruit  that  heavy  thin- 
ning is  necessary,  and  the  little  that  has  been  injured  by  the  worms  up 
to  thinning  time  is  removed  in  that  process.  If  this  thinning  is  done 
before  many  of  the  worms  have  left  the  fruit  and  the  apples  removed 
are  properly  disposed  of,  it  can  not  but  have  a  beneficial  effect  in  reduc- 
ing the  number  of  parents  for  the  next  generation. 

Under  the  conditions  occurring  in  this  valley  all  the  work  of  the  first 
two  campaigns  is  directed  primarily  toward  preventing  the  laying  of  a 
large  number  of  eggs  for  the  midsummer  generation.  The  third  cam- 
paign is  the  most  important  one,  and  would  be  the  only  important  one 
but  for  the  fact  that  the  majority  of  the  insects  killed  by  a  spray  in 
this  section  are  killed  only  after  the  worms  have  marred  the  fruit. 
Their  work  is  often  supposed  to  be  done  by  the  little  green  beetle  with 
black  spots  (Diabrotica  soror)  and  does  not  really  injure  the  apple  for 
use,  but  is  very  objectionable  from  a  commercial  standpoint,  since  the 
fruit  is  no  longer  of  first  quality. 

Very  few  worms  will  be  able  to  develop  in  fruit  which  is  kept  poisoned 
from  midsummer  until  fall,  but  the  fruit  may  be  badly  marked  by  the 
entrances  just  alluded  to.  It  will  not  do,  therefore,  in  most  localities 
to  neglect  the  earlier  campaigns,  even  though  the  third  is  the  most 
important. 

The  method  of  spraying  is  the  same  as  in  the  second  campaign,  but 
the  foliage  becomes  more  susceptible  to  injury  late  in  the  season,  both 
because  there  may  be  an  accumulation  of  poison  in  the  leaves  from 
earlier  applications,  and  from  the  fact  that  older  foliage  is  less  resistant 
to  the  poisonous  action  of  arsenic*  The  sprayer  should  look  for  evi- 
dences of  injury  and,  if  necessary,  change  to  a  less  injurious  arsenical. 


*Arsenic  poisoning  is  of  two  sorts :  the  acute  and  the  chronic ;  the  former  is  more 
common  on  young  foliage  in  the  spring  when  grossly  careless  methods  have  been 
employed,  and  consists  in  the  sudden  dying  and  drying  up  of  the  edge  of  the  leaf,  or  of 
the  whole  leaf,  as  though  killed  by  heat,  and  is  quite  appropriately  called  "burning." 
The  chronic  poisoning  is  very  gradual  in  its  action,  and  resembles  the  normal  ripening 
of  the  leaf  in  the  fall.  It  is  hardly  distinguishable  from  the  effect  of  drought,  or  the 
injury  by  a  sap-sucking  insect,  and  is  most  likely  to  show  itself  where  the  tree  or  branch 
is  already  suffering  from  one  of  these  other  troubles. 

When  using  the  lead  arsenate  there  is  very  little  danger  from  this  source,  and  possibly 
the  new  paris-green-oil-lime  mixture  may  be  a  complete  preventive.  With  other 
arsenicals  care  must  be  observed  toward  the  end  of  the  season. 


DIRECTIONS    FOR    SPRAYING    FOR    THE    CODLING-MOTH.  17 

We  desire  to  secure  the  co-operation  of  orchardists  in  all  parts  of  the  State  in  making 
observations  on  the  time  of  pupation  of  the  first  brood  of  codling-moth  larvae  in  each 
section.  Blanks  like  the  following  and  envelopes  to  contain  specimens  will  be  sent  to 
any  who  will  volunteer  in  this  work. 


PUPATION  RECORD 
To  Determine  Date  to  Spray  for  Codling-Moth  in  Third  Campaign. 

Name  of  observer 

Address 

Location  of  orchard 

Number  of  bands 

Put  bands  around  a  number  of  trees  and  examine  them  each  week. 
Provide  a  tight  tin  box  to  contain  specimens.  As  soon  as  you  find 
worms  beneath  the  bands  put  them  in  the  tin  box,  noting  hereon  the 
date  and  number  of  worms  found.  Keep  the  box  in  the  cupboard  pro- 
vided for  observation  of  the  second  campaign.  The  next  week  before 
going  around  to  examine  the  bands,  see  if  any  of  the  worms  in  the 
tin  box  have  transformed  into  brown  pupse;  kill  them  by  puncturing 
with  a  pin  and  place  in  envelope  A,  the  next  week  in  envelope  B,  etc. 

t..  Number  of  Pupae        t?„„^i^™  Number  of  Worms  taken  from 

Date-  in  Box.  envelope.  Bands  and  put  in  Box. 


B  

Spray  now  unless  you  have  sprayed  within  three  weeks,  and  repeat  in  three  or  four 
weeks'  intervals  as  long  as  pupae  continue  to  appear  in  the  box. 

c        


D 
E 
F 
G 
H 
I 
J 
K 
L 
M 
O 


Actual  dates  of  sprayin: 


Send  this  record,  and  the  envelopes  containing  specimens  for  accurate 
identification,  to  C.  W.  WOODWORTH,  Agricultural  Experiment 
Station,  Berkeley,  California. 


DIRECTIONS   FOR    SPRAYING   FOR   THE    CODLING-MOTH.  19 

The  time  to  begin  the  sprayings  of  this  campaign  can  be  deter- 
mined by  the  use  of  bands.  These  have  been  widely  used  as  a  remedy 
for  the  codling-moth,  but  are  not  effective  enough  to  be  of  much  value; 
we  could  not  see  that  the  use  of  bands  accomplished  enough  to  warrant 
their  use  as  a  supplementary  measure  in  connection  with  spraying. 
We  are  not  yet  ready  to  condemn  their  use  in  this  way,  and  can  com- 
mend them  as  an  index  to  spraying  operations. 

When  the  spring  generation  of  worms  is  full  grown,  they  leave  the 
fruit  and  seek  a  place  in  which  to  go  through  their  transformations. 
If  there  are  bands  on  the  tree,  enough  will  select  this  place  to  give  a 
good  idea  of  the  general  condition  of  the  brood. 

After  spinning  their  cocoons  the  worms  soon  assume  the  pupa  con- 
dition and  are  then  somewhat  spindle-shaped  and  brown  in  color,  and 
in  a  few  days  they  come  forth  as  perfect  moths  ready  to  lay  eggs  for 
the  second  generation  of  worms.  Within  a  couple  of  weeks  from  the 
time  the  first  pupse  are  discovered  the  orchard  should  be  well  poisoned, 
if  not  very  recently  sprayed,  for  the  late  worms  of  the  first  generation. 
This  should  be  repeated  often  enough  to  keep  everything  poisoned  to 
the  end  of  the  season  in  the  fall. 

Apparently  the  season  ends  at  quite  different  dates  in  different  years, 
for  often  the  eggs  of  the  moth  will  be  found  very  abundantly  on  the 
apples  at  picking  time,  and  the  same  variety  may  in  another  year  be 
quite  free  from  eggs.  This  is  probably  because  the  conditions  causing 
the  hibernation  of  the  worms  became  effective  earlier  in  the  season. 

When  the  conditions  favoring  hibernation  are  present,  the  worm 
simply  becomes  quiescent  within  its  cocoon,  instead  of  transforming 
into  a  pupa,  and  may  pass  half  the  year  in  this  stupor.  As  soon  as 
this  occurs,  which  we  will  know  when  pupse  cease  to  be  produced,  the 
season's  fight  against  the  codling-moth  may  be  considered  at  an  end. 

THE    YEAR'S    SPRAYING    PROGRAM. 

The  foregoing  account  may  seem,  at  first  sight,  to  be  very  complicated, 
but  when  applied  to  the  conditions  obtaining  in  most  localities  will  at 
once  simplify  itself.  For  instance,  in  the  coldest  localities  there  may  be 
but  one  brood,  in  which  case  no  summer  pupae  will  be  produced  and  the 
third  campaign  disappears.  Here,  also,  the  blossoms  may  open  almost 
simultaneously,  making  the  first  campaign  consist  of  a  single  spraying. 
The  first  generation  of  moths  may  also  come  out  with  the  blossoms,  so 
as  to  require  nothing  additional. 

Where  it  is  a  little  warmer  the  moths  may  come  out  later,  requiring 
one  spraying  in  both  first  and  second  campaigns;  but  the  moths  remain 
one-brooded,  so  that  the  third  campaign  is  barred  out.  If  they  become 
double-brooded,  then  probably  the  smallest  number  of  sprayings  will 
be  two  in  the  spring  and  one  in  midsummer. 


20  UNIVERSITY    OF   CALIFORNIA EXPERIMENT   STATION. 

In  the  still  warmer  locations,  the  number  of  sprayings  will  increase,, 
until  perhaps  as  many  as  three  or  four  in  each  campaign  may  be 
needed.  It  is  impossible  to  give  specific  directions  for  each  locality 
until  sufficient  data  have  been  obtained  by  making  the  observations 
through  a  series  of  years,  as  indicated  in  this  bulletin. 

RESUME. 

The  codling-moth  was  found  controllable  by  the  use  of  arsenical 
sprays  in  every  district  studied. 

Paris  green  is  highly  satisfactory,  wherever  it  is  safe  to  foliage,  but 
in  some  localities  may  have  to  be  replaced  by  lime  arsenite  or  lead 
arsenate;  or,  possibly,  the  new  formula  of  paris  green,  oil,  and  lime 
may  prove  best. 

The  fight  against  the  codling-moth  may  be  divided  into  three  cam- 
paigns; the  timing  of  each  must  be  determined  for  each  region. 

The  first  campaign  is  intended  for  the  poisoning  of  the  calyx  cup  of 
the  apple,  and  requires  spraying  from  above  and  more  than  one  appli- 
cation, if  the  blossoms  are  not  uniform  in  time  of  opening. 

The  second  campaign  is  timed  by  the  appearance  of  the  moth  in  the 
spring,  and  requires  a  method  of  spraying  different  from  that  of  the 
first  campaign,  the  idea  being  to  cover  every  part  of  the  leaf  and  fruit 
with  the  poison. 

The  third  campaign  is  for  the  later  worms,  and  the  times  of  beginning 
and  closing  this  attack  are  determined  by  the  production  of  pupae,  from 
which  moths  will  hatch  that  season  and  lay  eggs  for  another  brood  of 
worms.  The  danger  to  foliage  by  the  poison  is  greatest  during  this 
campaign. 

Orchardists  are  solicited  to  aid  the  Station  in  its  further  study  of  the 
insect,  by  making  observations  in  their  own  localities  of  the  facts  upon 
which  the  timing  of  the  applications  in  each  of  these  campaigns  must 
be  based. 


